Hiding a user means hiding the users hometopic in the Main web. You set an ALLOWTOPICVIEW setting in the users topic. Only the admin and the users granted access can see the content of the users topic.

This does not hide the users name from appearing in topic that the user has edited.

When you do not have view access to a users home topic ....

The users topic will not show up in searches

The user will not be shown as a member of a group with GROUPINFO or GROUPS

You can also hide a Group topic from view. Then the group is not listed with GROUPINFO or GROUPS.

There is a subtle difference in operation when using "Hidden" groups, especially when nested in other groups. Consider the following group structure.

SomeGroup

UserOne

SomeHiddenGroup (VIEW is denied to guest)

UserTwo

SecretUser (VIEW is denied to guest)

If the Guest uses %GROUPINFO% or %GROUPS% to list SomeGroup, they will see UserOne and UserTwo. The SecretUser will not be revealed, but SomeHiddenGroup will be expanded.

If the Guest uses %GROUPINFO% to list groups without expanding nested groups (or visits the WikiGroups topic), then SomeHiddenGroup will not be revealed, either directly or as a member of SomeGroup.

By comparing the expanded list of users of SomeGroup with the un-expanded list, it is possible to infer by the presence of UserTwo that there is a hidden group, but the hidden group name or the hidden users are not revealed.

The important thing to remember: If you need to hide the existance of users, protect their user topics. It is not enough to protect the group topic.